How is the Periodic Table Organized?

The periodic table is organized with vertical columns and horizontal rows. The vertical columns of the periodic table (there are 18) are called groups or families. Elements in the same group or family have similar but not identical characteristics. The horizontal rows are called periods. Elements in a period are not like properties. As a rule, the first element in a period is usually an active solid, and the last element in a period is always an inactive gas.